[How Useful is an Olfactory Test for Diagnosing Alzheimer's Syndrome?].

Olfactory dysfunction is closely associated with cognitive dysfunction, and it is a known risk factor for the development of dementia. However, pathological studies revealed it to be more closely associated with the degree of Lewy body pathology than with the severity of pathological changes in Alzheimer's. Notably, more than half the patients with clinically diagnosed Alzheimer's dementia have accompanying Lewy body pathology, and olfactory loss may serve as an important symptom for suggesting its presence and enabling its detection.